U.S. patent number 6,714,139 [Application Number 09/756,221] was granted by the patent office on 2004-03-30 for periphery monitoring device for motor vehicle and recording medium containing program for determining danger of collision for motor vehicle.
This patent grant is currently assigned to Yazaki Corporation. Invention is credited to Naoto Ishikawa, Masaki Saito.
United States Patent |
6,714,139 |
Saito , et al. |
March 30, 2004 |
Periphery monitoring device for motor vehicle and recording medium
containing program for determining danger of collision for motor
vehicle
Abstract
The positions of an object on the sideward position of a vehicle
are detected at prescribed time intervals. An expected locus of the
object is computed on the basis of the positions of the object
detected at the prescribed time intervals. An expected locus of the
vehicle is also computed. It is determined whether or not there is
a danger of collision on the basis of both the expected loci of the
object and the vehicle. In this configuration, a periphery
monitoring apparatus can be proposed which is capable of
determining the danger of collision on the basis of the mutual
movements of the vehicle and object.
Inventors: |
Saito; Masaki (Shizuoka,
JP), Ishikawa; Naoto (Shizuoka, JP) |
Assignee: |
Yazaki Corporation (Tokyo,
JP)
|
Family
ID: |
18534241 |
Appl.
No.: |
09/756,221 |
Filed: |
January 9, 2001 |
Foreign Application Priority Data
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|
|
|
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Jan 14, 2000 [JP] |
|
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2000-005597 |
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Current U.S.
Class: |
340/903; 340/436;
701/301; 340/938 |
Current CPC
Class: |
G01S
11/12 (20130101); G01S 17/931 (20200101); G01S
15/931 (20130101) |
Current International
Class: |
G01S
17/93 (20060101); G01S 17/00 (20060101); G08G
001/16 () |
Field of
Search: |
;340/903,904,438,441,933,938,436 ;701/301,302 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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41 15 747 |
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Nov 1992 |
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DE |
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197 35 414 |
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Feb 1998 |
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DE |
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198 21 803 |
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Nov 1999 |
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DE |
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0 020 269 |
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Dec 1980 |
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EP |
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0 433 351 |
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Jun 1991 |
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EP |
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0 590 588 |
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Apr 1994 |
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EP |
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0 817 152 |
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Jan 1998 |
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EP |
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2 020 938 |
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Nov 1979 |
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GB |
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WO09/02985 |
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Mar 1990 |
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WO |
|
Other References
Electronics Feb.1, 1963 pp. 27-31 "New Air-Traffic System Predicts
Flight Paths": SD Moxley and JA Inderhees. .
German Office Action dated Nov. 7, 2002, with translation. .
Patent Abstracts of Japan, Pub. No. 56034546 A, Apr. 6,
1981..
|
Primary Examiner: Pham; Toan Ngoc
Attorney, Agent or Firm: Armstrong, Kratz, Quintos, Hanson
& Brooks, LLP.
Claims
What is claimed is:
1. A periphery monitoring apparatus for a vehicle traveling on
ground comprising: object position detecting means having an
in-vehicle monitoring means for monitoring the periphery of the
vehicle to produce a monitoring signal representative of an
environmental condition, said object position detecting means for
detecting the positions of an object on coordinates set with
respect to the position and monitoring direction of said monitoring
means and at prescribed time intervals on the basis of said
monitoring signal; movement quantity detecting means for detecting
the position and movement quantity of said monitoring means in the
monitoring direction which moves for a prescribed time while the
vehicle moves; expected object locus computing means for computing
a real locus of said object on the basis of the positions of said
object and said movement quantity of the monitoring means and
computing an expected locus of said object on the basis of said
real locus of the object; expected vehicle locus computing means
for computing an expected locus of the vehicle; and danger
determining means for determining whether or not there is a danger
of collision between the object and the vehicle on the basis of
both the expected loci of the object and the vehicle.
2. A periphery monitoring apparatus for a vehicle traveling on
ground according to claim 1, wherein said monitoring means is an
image pick-up means which produces a plurality of image signals
which are obtained by picking up the periphery of the vehicle from
two positions apart from each other by a prescribed distance, and
said object position detecting means detects the positions of the
object on the basis of the plurality of image signals produced from
said image pick-up means.
3. A periphery monitoring device for the vehicle according to claim
2, further comprising: means for detecting a speed of the object on
the basis of said real locus of the object; and means for detecting
a speed of the vehicle, wherein said danger determining means
whether or not there is a danger of collision between the object
and the vehicle on the basis of both the expected position of the
object computed on the basis of the expected locus and speed of the
object and the expected position of the vehicle computed on the
basis of the expected locus and speed of the vehicle.
4. A periphery monitoring apparatus for the vehicle according to
claim 2, wherein said object position detecting means detects each
of a plurality of objects on the coordinates when they are picked
up by said image pick-up means; said expected object locus
computing means distinguishably computes an expected locus of each
of said objects; and danger determining means for determining
whether or not there is a danger of collision between the object
and the vehicle on the basis of both the expected loci of each of
said objects and the vehicle.
5. A periphery monitoring apparatus for the vehicle according to
claim 4, further comprising: collision expected time computing
means for computing an expected collision time on the basis of said
expected position of the object and said expected position of the
vehicle when said danger determining means determines that there is
a danger; and warning issuing means for issuing multi-step warnings
according to said collision expected time.
6. A periphery monitoring apparatus for the vehicle according to
claim 4, further comprising: collision expected time computing
means for computing an expected collision time on the basis of said
expected position of the object and said expected position of the
vehicle when said danger determining means determines that there is
a danger; and warning issuing means for issuing multi-step warning
according to said collision expected time.
7. A periphery monitoring apparatus for the vehicle according to
claim 1, further comprising warning means for issuing a warning
when said danger determining means determines that there is a
danger.
8. A recording medium containing a processing program for
determining a danger of collision of a vehicle traveling on ground
and an object by a computer, said processing program to be executed
by said comprising the steps of: detecting positions of an object
on the periphery of the vehicle at prescribed time intervals;
computing an expected locus of the object on the basis of the
positions of the object detected by said object position detecting
means; computing an expected locus of the vehicle; and determining
whether or not there is a danger of collision between the object
and the vehicle on the basis of both the expected loci of the
object and the vehicle.
9. A recording medium containing a processing program for
determining a danger of collision of a vehicle traveling on ground
and an object by a computer, said processing program to be executed
by said computer comprising the steps of: acquiring a monitoring
signal representative of an environmental condition produced from
an in-vehicle monitoring means for monitoring the periphery of the
vehicle; detecting the positions of an object on coordinates at
prescribed time intervals on the basis of said monitoring signal;
detecting the position and movement quantity of said monitoring
means in a monitoring direction which moves for a prescribed time
while the vehicle moves; computing a real locus of said object on
the basis of the positions of said object and said movement
quantity of the monitoring means; computing an expected locus of
said object on the basis of said real locus of the object;
computing an expected locus of the vehicle; and determining whether
or not there is a danger of collision between the object and the
vehicle on the basis of both the expected loci of the object and
the vehicle.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an periphery monitoring device for
a motor vehicle (hereinafter referred to as "in-vehicle periphery
monitoring device) and a recording medium containing a program for
determining danger of collision for the vehicle. More particularly,
the present invention relates to an in-vehicle periphery monitoring
device for monitoring an object such as a walker or bicycle on the
periphery of the motor vehicle to assist assertion of safety by a
driver, and a recording medium containing a processing program for
determining the danger of collision between the vehicle and the
object by means of a computer.
2. Description of the Related Art
While a driver operates a motor vehicle or car, there is a range
out of his filed of view on the periphery of the motor vehicle even
if his filed of view is supplemented by a fender mirror or back
mirror. Particularly, when he operates a large car such as a truck
or bus, he has a wider blind spot. Therefore, for example, when the
vehicle having a right handle turns left, the driver cannot find a
low object passing by the vehicle such a s a child walking along a
sidewalk toward the vehicle, thus leading to an accident or
catching or cutting off him. In order to obviate such difficulty,
an in-vehicle periphery monitoring device has been proposed which
can insure the side field of view using the side image acquired by
the camera mounted on a large vehicle such as a bus to carry out
the periphery monitoring in turning right or left.
However, when the driver uses the in-vehicle periphery monitoring
device, he must eye the display device to make assertion of safety,
which is dangerous in the assertion of safety. In order to avoid
such danger, the following cutting-off accident preventing device
has been proposed. The cutting-off accident preventing device
decides whether or not there is an object within a prescribed area
in the vicinity of the vehicle on the basis of the image picked up
by a camera attached to the side of the vehicle. If "YES", when a
handle operation or winker operation is carried out, the
cutting-off accident preventing device gives a warning that there
is possibility of cutting off the object. This cutting-off accident
preventing device makes it unnecessary to verify safety by eyeing
and informs the danger of cutting-off by the warning, thereby
improving the safety during driving.
Meanwhile, where the object moves like a walker or bicycle, even if
there is the object in vicinity of the vehicle, if it moves in the
direction leaving from the vehicle, as the case may be, there is no
possibility of contact of the vehicle with the object. Conversely,
even if there is no object in the vicinity of the vehicle, if the
object moves in the direction of approaching the vehicle, there is
strong possibility of collision between the vehicle and the object.
Namely, the danger of collision between the vehicle and the object
does not necessarily depend on only the distance between the
vehicle and the object.
However, the above cutting-off accident preventing device only
decides the danger of cutting-off or collision in turning left or
right according to whether or not there is the object within the
prescribed region in the vicinity of the vehicle, and cannot detect
the danger of collision accurately.
SUMMARY OF THE INVENTION
In view of the problems as described above, a primary object of the
present invention is to provide an in-vehicle periphery monitoring
device which can decide the danger of collision between a vehicle
and an object on the basis of the relative movements of the vehicle
and object.
Another object of the invention is to provide a recording medium
containing a processing program for properly deciding the danger of
collision between the vehicle and the object.
In order to attain the first object, in accordance with the
invention, as seen from the basic structural diagram of FIG. 1,
there is provided a periphery monitoring device for a vehicle
comprising: object position detecting means 51a for detecting
positions of an object on the periphery of a vehicle at prescribed
time intervals; expected object locus computing means 51b for
computing an expected locus of the object on the basis of the
positions of the object detected by the object position detecting
means; expected vehicle locus computing means 51c for computing an
expected locus of the vehicle; and danger determining means 51d for
determining whether or not there is a danger of collision between
the object and the vehicle on the basis of both the expected loci
of the object and the vehicle.
In this configuration, since it is determined whether or not there
is a danger of collision between the object and the vehicle on the
basis of both the expected loci of the object and the vehicle, the
danger can be determined accurately.
Preferably, the periphery monitoring device for a vehicle, further
comprises: means for detecting a speed of the object; and means for
detecting a speed of the vehicle, wherein the danger determining
means determines whether or not there is a danger of collision
between the object and the vehicle on the basis of both the
expected position of the object computed on the basis of the
expected locus and speed of the object and the expected position of
the vehicle computed on the basis of the expected locus and speed
of the vehicle.
In this configuration, since the danger is determined on the basis
of the speed of each of the object and vehicle as well as the loci
thereof, the danger can be determined more accurately.
In accordance with this invention, there is provided a periphery
monitoring apparatus for a vehicle comprising: object position
detecting means having an in-vehicle monitoring means for
monitoring the periphery of a vehicle to produce a monitoring
signal representative of an environmental condition, the object
position detecting means for detecting the positions of an object
on coordinates set with respect to the position and monitoring
direction of the monitoring means at prescribed time intervals on
the basis of the monitoring signal; movement quantity detecting
means for detecting the position and movement quantity of the
monitoring means in the monitoring direction which moves for a
prescribed time while the vehicle moves; expected object locus
computing means for computing a real locus of the object on the
basis of the positions of the object and the movement quantity of
the monitoring means and computing an expected locus of the object
on the basis of the real locus of the object; expected vehicle
locus computing means for computing an expected locus of the
vehicle; and danger determining means for determining whether or
not there is a danger of collision between the object and the
vehicle on the basis of both the expected loci of the object and
the vehicle.
In this configuration, since it is determined whether or not there
is a danger of collision between the object and the vehicle on the
basis of both the expected loci of the object and the vehicle, the
danger can be determined accurately.
In the periphery monitoring apparatus for a vehicle, preferably,
the monitoring means is an image pick-up means which produces a
plurality of image signals which are obtained by picking up the
periphery of the vehicle from two positions apart from each other
by a prescribed distance, and the object position detecting means
detects the positions of the object on the basis of the plurality
of image signals produced from the image pick-up means.
In this configuration, since the image pick-up means monitors the
object within a wider range which can be picked up, the danger of
collision can be determined more accurately.
It is preferred in the periphery monitoring apparatus for a vehicle
that the object position detecting means detects each of a
plurality of objects on the coordinates when they are picked up by
the image pick-up means; the expected object locus computing means
distinguishably computes an expected locus of each of the objects;
and danger determining means determines whether or not there is a
danger of collision between the object and the vehicle on the basis
of both the expected loci of each of the objects and the
vehicle.
In this configuration, even there are a plurality of objects, the
danger can be determined for each of the objects so that it can be
determined more accurately.
The periphery monitoring device for a vehicle, further comprises:
means for detecting a speed of the object on the basis of the real
locus of the object; and means for detecting a speed of the
vehicle, wherein the danger determining means determines whether or
not there is a danger of collision between the object and the
vehicle on the basis of both the expected position of the object
computed on the basis of the expected locus and speed of the object
and the expected position of the vehicle computed on the basis of
the expected locus and speed of the vehicle.
In this configuration, since the danger is determined on the basis
of the speed of each of the object and vehicle as well as the loci
thereof, the danger can be determined more accurately.
Preferably, the periphery monitoring apparatus for a vehicle
further comprises waning means for issuing a warning when the
danger determining means determines that there is a danger.
In this configuration, a driver is beforehand informed of the
danger of collision.
The periphery monitoring apparatus for a vehicle, further
comprises: collision expected time computing means for computing an
expected collision time on the basis of the expected position of
the object and the expected position of the vehicle when the danger
determining means determines that there is a danger; and warning
issuing means for issuing multi-step warnings according to the
collision expected time.
In this configuration, the driver can be beforehand informed of the
degree of danger of collision.
In accordance with the second aspect of the invention, there is
provided a recording medium containing a processing program for
determining a danger of collision of a vehicle and an object by a
computer, the processing program to be executed by the comprising
the steps of: detecting positions of an object on the periphery of
a vehicle at prescribed time intervals; computing an expected locus
of the object on the basis of the positions of the object detected
by the object position detecting means; computing an expected locus
of the vehicle; and determining whether or not there is a danger of
collision between the object and the vehicle on the basis of both
the expected loci of the object and the vehicle. Further, there is
provided a recording medium containing a processing program for
determining a danger of collision of a vehicle and an object by a
computer, the processing program to be executed by the computer
comprising the steps of: acquiring a monitoring signal
representative of an environmental condition produced from an
in-vehicle monitoring means for monitoring the periphery of a
vehicle; detecting the positions of an object on coordinates at
prescribed time intervals on the basis of the monitoring signal;
detecting the position and movement quantity of the monitoring
means in a monitoring direction which moves for a prescribed time
while the vehicle moves; computing a real locus of the object on
the basis of the positions of the object and the movement quantity
of the monitoring means; computing an expected locus of the object
on the basis of the real locus of the object; computing an expected
locus of the vehicle; and determining whether or not there is a
danger of collision between the object and the vehicle on the basis
of both the expected loci of the object and the vehicle.
In these configurations according to this aspect, since it is
determined whether or not there is a danger of collision between
the object and the vehicle on the basis of both the expected loci
of the object and the vehicle, the danger can be determined
accurately.
The above and other objects and features of the invention will be
more apparent from the following description taken in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing a basic configuration of an
in-vehicle side monitoring device according to the present
invention;
FIG. 2 is a block diagram showing an embodiment of the in-vehicle
side monitoring device according to the invention;
FIG. 3 is a perspective view of the manner in which a camera is
mounted according to the embodiment of the invention;
FIG. 4 is a flowchart showing the processing procedure in a CPU
constituting the in-vehicle shown in FIG. 2;
FIG. 5 is a view for explaining the correction of a depression
angle of the camera according to this embodiment;
FIGS. 6A and 6B are views for explaining the measurement of a
three-dimensional position according to this embodiment;
FIGS. 7A to 7D are views for explaining the removal of a road
surface image;
FIGS. 8A to 8C are views for explaining the detection of an object
edge according to this embodiment;
FIGS. 9A and 9B are views for explaining the operation of the CPU;
and
FIGS. 10A and 10B are views for explaining the decision of danger
carried out by the CPU.
FIGS. 11A and 11B are views for explaining the decision of danger
carried out the CPU.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, an explanation will be given of an
embodiment of the present invention.
FIG. 2 shows the in-vehicle periphery monitoring device according
to the present invention. In FIG. 2, reference numeral 1 denotes an
image pick-up unit mounted in a vehicle to monitor the periphery of
a vehicle; 2 denotes a helm detecting unit for detecting turning
information of the vehicle; 3 a speed detecting unit for detecting
the speed of the vehicle; 4 a storage unit for storing image
information and others; 5 a microcomputer (.mu.COM); 6 a display
unit; and 7 a sound unit for issuing warning sound or audio
guidance.
The image pick-up unit 1 includes a right CCD camera (image pick-up
means) 11R, a left CCD camera (image pick-up means) 11L, a right
image plane 12R on which the image information picked up by the
right CCD camera 11R is projected and a left image plane 12L on
which the image information picked up by the left CCD camera 11L is
projected. As shown in FIG. 3, the image pick-up unit 1 is located
at the position of height H at the front sideward position of the
vehicle 100 so that it is oriented outwardly from the vehicle. The
pair of CCD cameras 11 constituting the image pick-up unit 1 are
located in parallel apart from each other by a prescribed distance
at an angle .theta.s of depression. Therefore, the image pick-up
unit 1 picks up the a monitoring region 100a [100a(11R) and
100a(11L)] in the front sideward area of the vehicle.
The helm detecting unit 2 includes a handle helm sensor for
detecting the rotating quantity and direction of the handle and a
steering angle sensor for detecting the steering angle of a
steering wheel (generally front wheel) (both sensors are not
shown), and produces turning information inclusive of the turning
direction of a vehicle and steering angle detected by these
sensors. The speed detecting unit 3 may be a driving sensor (not
shown) which produces a pulse signal whenever the vehicle runs by a
unit distance to provide a vehicle speed computed on the basis of
the pulse signal as speed information.
The storage unit 4 includes a right frame memory 41R for
temporarily storing, as a right image signal, the image information
projected on the right image plane 12R of the image pick-up unit 1;
a left frame memory 41L for temporarily storing, as a left image
signal, the image information projected on the left image plane 12L
of the image pick-up unit 1; a differential image memory 42 for
storing a differential image; a differentiated image memory 43 for
storing a differentiated image; and an edge image memory 44 for
storing an edge image (the differential image, differentiated image
and edge image will be described later). These memories 41 to 45
are constructed in a matrix with m rows and n columns, e.g. as a
array of 512 (m).times.512 (n) pixels. Each of the pixels
constituting the memory contains luminance data with e.g. 256
levels of gray.
The .mu.COM 5 includes a ROM 52 which is a recording medium which
stores an operation program for deciding the danger of collision
between the vehicle and object, a CPU 51 which operates according
to the operation program and a RAM 53 for temporarily storing the
information required when the CPU 51 operates. The display unit 6
has a display 61 on which the image picked up by the camera 11 or
message for a driver is displayed on the basis of the displaying
image signal supplied from the CPU 51. The sound unit 7 issues
buzzer sound or audio guidance from a speaker 71 on the basis of
the buzzer sound signal or audio guidance supplied from the CPU
51.
The CPU 51 within the .mu.COM 5 performs processing of detecting,
every prescribed times .DELTA.t's, the position of an object on the
coordinates set with respect to the position of the CCD camera on
the basis of the image signals stored in the right frame memory 41R
and left frame memory 41L of the image pick-up unit 1 (object
position detecting means), processing of detecting the position and
the movement quantity of the CCD camera 11 in a monitoring
direction on the basis of the moving locus of the CCD camera 11
which moves during the prescribed time (movement quantity detecting
means), processing of computing the real locus of the object on the
basis of the positions of the object detected at two timings at the
interval of the prescribed time .DELTA.t and movement quantity
detected by the movement quantity detecting means and computing the
expected locus of the object on the basis of the real locus thus
computed (expected object locus computing means), and processing of
detecting the speed of the object on the basis of the real locus of
the object thus expected, and processing of computing the expected
positions of the object after .DELTA.t1, .DELTA.t2 . . . .DELTA.tn
on the basis of the expected object locus and the object speed.
The CPU 51 performs processing of computing a vehicle expected
locus on the basis of the turning information from the helm
detecting unit 2 (expected vehicle locus computing means),
processing of computing the expected positions of the vehicle after
.DELTA.t1, .DELTA.t2 . . . .DELTA.tn on the basis of the expected
vehicle locus and the speed information supplied from the speed
detecting unit 3, processing of determining whether or not there is
danger of collision between the vehicle and object on the basis of
the expected object position and the expected vehicle position
(danger determining means) and processing of issuing a warning when
it is decided that there is danger of collision (warning issuing
means).
Now referring to the flowchart of FIG. 4, an explanation will be
given of the operation of the in-vehicle periphery monitoring
device having a configuration described above.
CPU 51 starts to operate when the ignition switch (not shown) is
turned on. In an initial step (not shown), initial settings are
made for the respective areas of the .mu.COM 5. Thereafter, the
processing proceeds to initial step S1.
In step S1, the image signal picked up by the image pick-up unit 1
at timing t is once projected on the image planes 12R and 12L and
are stored in the right frame memory 41R and the left frame memory
41L as the luminance data for each of the pixels. In step S2,
processing of detecting the presence/absence of an object is
performed on the basis of the image signal stored in step S1.
In step S3, it is decided whether or not the presence of the object
has been detected in step S2. If YES (there is the object), the
processing proceeds to step S4. In step S4, processing of detecting
the position of the object on the coordinates set with respect to
the position of the CCD camera 11 is performed. If NO in step S3,
the processing proceeds to step S6.
Now, a detailed explanation will be given of the processing of
detecting the presence/absence of the object in step S2 and the
processing of detecting the object position in step S4. In the
processing of detecting the presence/absence of the object, CPU 51
performs removal of a background image (image at height of "0") and
creation of an edge image of the object. For the purpose of
facilitating the explanation of these kinds of processing, the
processing of detecting the object in step S4 will be first
explained.
The image pick-up unit 1, i.e. CCD cameras 11, as explained in
connection with FIG. 3, is installed at the depression angle of
.theta.s at the front sideward position of the vehicle, picks up
the monitoring area 100a. Therefore, the image picked up by the
image pick-up unit 1 is an image taken with respect to its
location. Thus, the position of the object is taken with respect to
its location of the image pick-up unit. As understood from the
above explanation, the image pick-up unit 1 mounted in the vehicle
serves as a monitoring means which monitors the periphery of the
vehicle and also produces the signal indicative of the position of
the object on the coordinates set with respect to the location of
the image pick-up unit 1 (referred to as "camera position"). For
the sake of explanation, as shown in FIG. 5, the coordinates set
with respect to the above location are represented by X', Y' and
Z', while those on the road are represented by X, Y and Z.
On the X'Y'Z'-coordinate system, as seen from FIG. 6A, the Z'-axis
is defined as a lens optical axis of each of the CCD cameras 11;
the X'-axis is defined as an axis in parallel to the road surface;
and the Y'-axis is defined as an axis orthogonal to both Y' and Z'
axes. Therefore, the right CCD camera 11R and left CCD camera 11L
are arranged so that their lens optical axes are coincident with
the Z'-axis. With respect to the X'-axis, the CCD cameras 11 are
arranged so that their center points are located on the X'-axis
apart from each other by a prescribed distance dXa. For the purpose
of facilitating the following explanation, the origin O of the X',
Y' and Z' axes is defined as the center of the lens of the left CCD
camera 11R.
The point P (X.sub.P ', Y.sub.P ', Z.sub.P ') on the object
picked-up by the CCD cameras 11 is held as P.sub.R (x.sub.RP,
y.sub.RP) in the right frame memory 41R and held as P.sub.L
(x.sub.LP, y.sub.LP) in the left frame memory 41L. The Z'
coordinate Z.sub.P ' of the point P can be acquired in similarity
of a triangle as seen from the schematic view of the X'Z' plane in
FIG. 6B. Namely, the coordinate Z.sub.P ' can be expressed by
Equation (1)
where
dxa is a distance between both lenses
f is a focal distance of each lens
Likewise, the X' coordinate X.sub.P ' of the point P can be also
acquired in similarity of a triangle as seen from the schematic
view of the X'Z' plane in FIG. 6B. The Y' coordinate Y.sub.P ' of
the point P can be also acquired similarly on the assumption of the
Y'Z' plane not shown. Thus, the X' coordinate X.sub.P ' and the Y'
coordinate Y.sub.P ' can be expressed by Equations (2) and (3),
respectively. ##EQU1##
Incidentally, with respect to the coordinate X.sub.P ', if the
standard coordinates are set between the right CCD camera 11R and
the left CCD camera 11L, a difference between the coordinate
X.sub.P ' calculated by Equation (2) and 1/2 of the distance of the
distance dxa between both lenses may be taken.
Since the point P (X.sub.P ', Y.sub.P ', Z.sub.P ') in the X'Y'Z'
coordinate system calculated by Equations (1) to (3) represents the
coordinate value on the coordinate system set with respect to the
camera position, this coordinate value must be converted into that
in the XYZ coordinate system on the road surface. In this case,
assuming that the depression angle of the image pick-up unit 1 (CCD
cameras 11) is .theta..sub.s, the relationship between the
coordinate (X.sub.P ', Y.sub.P ', Z.sub.P ') of the point P in the
X'Y'Z' coordinate system and the XYZ coordinate system set with
respect to the road surface is set as shown in FIG. 5.
Thus, the coordinates (Z.sub.P ', Y.sub.P ', X.sub.P ') calculated
by Equations (1) to (3) can be converted into the coordinate
(X.sub.P, Y.sub.P, Z.sub.P) by implementing the following Equations
(4) to (6).
On the basis of Equations (1) to (6), an explanation will be given
of the processing of detecting the presence/absence of the object
by CPU 51 in step S2. First, removal of a background image (the
image at height of 0) will be explained.
FIG. 7A shows the right image picked up by the right CCD camera 11R
and held in the right frame memory 41R. In FIG. 7A, reference
numeral 300 denotes a white line and reference numeral 240 denotes
a pole-like object.
Now, it is assumed that the entire right image held in the right
frame memory 32R is the image at a height of 0, i.e. the image
drawn on the road surface. On the basis of the right image thus
assumed, it is converted into the image picked up (projected) at
the position of the left CCD camera 11L (FIG. 7B).
The processing of conversion into the projected image will be
explained. It is assumed that the point P.sub.L (x.sub.LP,
y.sub.LP) of the projected image corresponding to the point P.sub.R
of the right image (x.sub.RP, y.sub.RP) is P.sub.L (x.sub.LP,
y.sub.LP). As seen from FIG. 3, assuming that the X' axis relative
to the camera and the X-axis relative to the road surface are in
parallel and x-axes of the scanning lines to be picked up by the
cameras (x.sub.L axis and x.sub.R axis in FIG. 6) are also in
parallel, the y.sub.L value and y.sub.R value of the image when the
same object has been picked up are equal to each other. Further,
assuming that the entire image is on the road, the value of Y.sub.P
in Equation (6) becomes zero. This leads to the following equations
(7) and (8).
By substituting Z.sub.P ' and Y.sub.P ' in Equation (1) and Y.sub.P
' in Equation (3) into Z.sub.P ' and Y.sub.P ' in Equation (8),
X.sub.LP ' can be acquired as expressed by Equation (9),
By computing Equations (8) and (9), .mu.COM 5 creates the projected
image (FIG. 7B).
Superposition of the projected image thus created on the left image
creates an image as shown in FIG. 7C. Namely, where the right image
picked up by the right CCD camera 11R is superposed on the left
image plane, the pattern inclusive of a white line drawn on the
road surface is coincident to that picked up by the left CCD camera
11L in their position and luminance, and a difference increases as
the location of the object becomes high from the road surface. When
the difference between the left image data and projected image data
is taken, the luminance of each of the pixels constituting the road
surface other than those of the object becomes zero or a value
approximate to zero. Assuming that values not larger than a
prescribed threshold value are zero, all the pixels take the value
of zero. In this way, in the differential image when the difference
between the left image data and projected image data is taken, as
shown in FIG. 7D, the road surface image (background image at the
height of 0) is removed and only the portion having some height is
taken as having the values other than 0. The differential image is
stored in the differential image memory 42 in the storage section
4.
Thus, the background image having the height of 0 is removed, and
only the image of the object having the height can be extracted.
Subsequently, the processing of edge extraction will be carried out
for the object image thus extracted in the manner described
below.
The processing of edge extraction is carried out on the basis of
the image information stored in the left frame memory 41L. On the
left image stored in the left frame memory 41L, The luminance
values Im,n of the image data in a matrix with m rows and n columns
are scanned in the horizontal direction, i.e. X'-axis direction in
FIG. 6. Computing Equation (10) provides a differentiated
image.
The differentiated image, as shown in FIG. 8B, results in an image
with longitudinal edge portions of "1" and with the remaining
portion of "0". The differentiated image is stored in the
differentiated image memory 43 of the storage unit.
The differentiated image thus acquired (FIG. 8B) and the
differential image held in the differential image memory 42
(acquired by the processing of removal of the road surface image)
are superposed to make their AND. Thus, the image of the object
edge with only the extracted edge portion of the object as shown in
FIG. 8C is created. The object edge image is stored in the edge
image memory 35.
Returning to the processing of FIG. 4, in step S3, it is decided
whether or not the object has been detected according to whether or
not the object edge image has been created. Namely, if the object
is picked up by the pick-up unit 1 and the object edge image
corresponding to the object thus picked up is created, the
processing proceeds to step S4. On the other hand, if the object is
not picked up by the pick-up unit 1 and hence the object edge image
is not created, the processing immediately proceeds to step S6. In
step S4, using Equations (4) to (6), the edge points of the created
object edge image is transformed into the coordinates in the XYZ
coordinate system on the road surface. The coordinates are stored
in the RAM 53. The processing proceeds to step S5.
In step S5, at a timing t as shown in FIG. 9A, the map data
representative of the positional relationship is created between
the vehicle 100A and object 240A on the X1Z1 coordinate system on
the road surface relative to the CCD cameras 11. The map data are
stored in the RAM 53.
The processing proceeds to steps S6 and S7. After a prescribed time
.DELTA. from the timing of step S1 or step S6 carried out
previously, the same processing as in the above steps S1 and S2 is
repeated to detect the presence or absence of the object. In step
S8, it is decided whether or not the object has been detected in
the processing of detecting the presence or absence of the object
in step S7. If YES, the processing proceeds to step S9. On the
other hand, if NO in step S8, it is determined that there is no
danger of collision between the object and the vehicle, the
processing returns to step S6.
In step S9, the same processing as in step S4 is carried out. At a
timing t+.DELTA. as shown in FIG. 9B, the position of The object
240B on the X2Y2 coordinate system relative to the CCD cameras 11
mounted in the vehicle 100B is computed and stored in the RAM 53.
In step S10, on the basis of the turning information from the helm
detecting unit 2 and the speed information from the speed detecting
unit 3, the moving locus L3 of the CCD camera 11 which has moved
during the prescribed time .DELTA.t according to the driving of the
vehicle is also detected. On the basis of the moving locus L3, the
position of the CCD cameras 11 and their movement quantity in the
monitoring direction is detected. Incidentally, when the CCD
cameras are turned according to the turn such as the left turn or
right turn of the vehicle, the movement quantity must be acquired
taking the turning angle in consideration.
On the basis of the movement quantity thus acquired and the
position of the object 240B on the X2Z2 coordinate system, the map
data representative of the positional relationship between the
vehicle 100B and object 240B on the X1Z1 coordinate system are
created. The map data are stored in the RAM 53.
In step S11, processing of detecting the same object is carried
out. This processing is referred to as taking the correlation
between the object detected at timing t and the object detected at
timing t+.DELTA.t. In this processing, the object image
representative of the object 240A picked up at timing t is checked
against that representative of the object 240B. If both images
match with each other, it is determined that both object 240A and
240B are the same object. Incidentally, while a plurality of
objects are picked up by the CCD cameras, the processing of
detecting the same object will be implemented for each of the
plurality of objects.
In step S12, it is decided whether or not there is the same object
in the processing of detecting the same object. If NO, the
processing returns to step S6. If YES, the processing proceeds to
step S13. In step S13, processing of computing an expected inner
wheel locus L22 and an expected outer wheel locus L22 is performed
on the basis of the turning information from the helm detecting
unit 2 as shown in FIG. 10A. Subsequently, in step S14, on the
basis of the speed information from the speed detecting unit 3 and
the expected loci L22 and L21, the expected positions of the
vehicle 100C, 100D, 100E, . . . after .DELTA.T1, .DELTA.T2,
.DELTA.T3, . . . are computed and stored in the RAM 53.
In step S15, processing of computing an expected object locus is
carried out. Specifically, the real locus L11 of the object is
computed on the basis of the positions of the objects 240A and 240B
detected at a prescribed time interval .DELTA.t which can be
regarded the same object as shown in FIG. 10A, and the locus L11
thus computed is extended to compute an expected object locus
L12.
In step S16, processing of computing an expected object position is
carried out. Specifically, the distance of the real object locus
L11 acquired in step S15 is divided by a prescribed time .DELTA.t
to obtain an object speed. On the basis of the speed thus obtained
and the expected object locus L12, the expected positions 240C,
240D, 240E, . . . .DELTA.T1, .DELTA.T2, .DELTA.T3, . . . are
computed and stored in the RAM 53. The processing by CPU 51
proceeds to step S17.
In step S17, it is decided whether or not the expected object loci
have been computed for all the objects correlated in the processing
of detecting the same object in step S11. If NO, the processing
from step S15 to step S16 is repeated. Thus, the expected object
positions are computed for all the objects. By repeating the
processing from step S15 to S16, the expected locus and hence
expected position of each of the objects which may be detected in
the processing of detecting the object positions in S4. If YES in
step S17, the processing proceeds to step S18.
In step S18, on the basis of the expected positions 240C, 240D,
240E, . . . of the object after .DELTA.T1, .DELTA.T2, .DELTA.T3, .
. . computed in step S16 and the expected positions 100C, 100D,
100E of the vehicle after .DELTA.T1, .DELTA.T2, .DELTA.T3, . . .
computed in step S14, it is decided whether there is danger of
collision therebetween. Specifically, when there is an object which
is approaching the vehicle (FIG. 10A) or an object which stands
still within the expected locus of the vehicle (FIG. 10B), it is
determined that there is danger of collision (YES). The processing
by CPU 51 proceeds to step S19. On the other hand, when the object
is leaving from the vehicle (FIG. 11A), or when the object is a
forward vehicle which runs at the speed equal to or higher than the
vehicle at issue (FIG. 11B), it is determined that there is no
danger of collision. Thus, the processing returns to step S6.
As described above, since the danger of collision is determined
taking not only the expected position of the vehicle but also that
of the object, it can be determined accurately.
Further, in step S19, the expected timing of collision is computed
by CPU 51 on the basis of the expected positions 240C, 240D, 240E,
. . . of the object after .DELTA.T1, .DELTA.T2, .DELTA.T3, . . .
and the expected positions 100C, 100D, 100E of the vehicle after
.DELTA.T1, .DELTA.T2, .DELTA.T3, . . . For example, in the case of
FIGS. 10A and 10B, the expected timing of collision is that after
.DELTA.T3. In this step, the CPU 51 serves as means for computing
the timing of collision.
Subsequently, in step S20 in which a warning is issued, a
multi-step buzzer ON signal or audio guidance signal corresponding
to the expected timings of collision computed in step S19 is
supplied to the speaker 71.
Specifically, if the expected timing of collision is earlier than a
prescribed timing, under the decision that there is a high degree
of danger, an audio guidance signal is issued so that the speaker
71 announces that "Collision occurs", "Immediately avoid the
collision". On the other hand, if the expected timing of collision
is not earlier than the prescribed timing, under the decision that
there is a low degree of danger, the audio guidance signal is
issued so that "Collision may occur", "Pay attention".
An image display signal is issued to display the images picked up
by the CCD cameras 11 on the display 61, and a display frame signal
is issued to display a display frame encircling the object with
possibility of collision. If there are plural objects with
possibility of collision, the warning adapted to the object with
the most expected early timing of collision is issued.
As described above, by issuing the multi-step warning according to
the timings of collision, not only the danger of collision between
the vehicle and the object but also the degree thereof is notified
to the driver beforehand. Thus, the collision between the vehicle
and the object can be prevented.
In the embodiment described above, the positional relationship
between the vehicle and the object was detected on the basis of the
images picked up by two CCD cameras. However, it may be detected on
the basis of the time taken for an ultrasonic signal transmitted
from an ultrasonic generator to reach a receiver or for laser light
emitted from a laser light source to reach the receiver. In this
case, the ultrasonic generator or the laser light source are
mounted on the vehicle instead of the two CCD cameras 11.
However, the laser light or ultrasonic signal permits the relative
position of only one object nearest to the vehicle to be detected.
In addition, in the embodiment described above, the objects
detected at timing t and timing t+.DELTA.t were correlated on the
basis of the images picked up by the CCD cameras 11. However, in
the detection of the object position using the laser light and the
ultrasonic signal, it is difficult to decide whether or not the
objects detected at a time interval .DELTA.t are the same object.
Therefore, in order to decide the danger between the vehicle and
the object more accurately, it is preferred to detect the relative
positions of the vehicle and objects on the basis of the images
picked up by the CCD cameras 11 capable of detecting the relative
positions of all the objects and the vehicle as in the embodiment
described above.
Further, in the embodiment described above, the danger of collision
between the object and the vehicle was determined on the basis of
the expected positions of the object after .DELTA.T1, .DELTA.T2,
.DELTA.T3 taking the speed and expected locus of the object in
consideration, . . . and the expected positions of the vehicle
after .DELTA.T1, .DELTA.T2, .DELTA.T3 taking the speed and expected
locus of the vehicle into consideration. However, when the object
which approaches the vehicle is detected on the basis of the
expected loci of the object and vehicle, it may be determined that
there is danger without taking the speeds of the object and vehicle
into consideration. In this case, the expected loci must be
computed taking a difference between the inner and outer wheels
into consideration. However, there is a case where there is no
danger of collision according to the speeds of the object and
vehicle even when the object approaches the vehicle. Therefore, in
order to determine the danger of collision between the vehicle and
the object more accurately, it is preferred to determine the danger
of collision on the basis of both expected positions of the vehicle
and the object as in the embodiment described above.
In the embodiment described above, the helm detecting unit 2 and
vehicle speed detecting unit 3 were adopted as the movement
quantity. However, for example, the GPS or gyrocompass may be used
to detect the movement quantity during a prescribed time .DELTA.t.
Further, in the embodiment described above, the operation of
periphery detection is started when the ignition switch is turned
on. However, when a winker is lit, or a car navigation instructs
right-turning or left-turning, the operation is started under the
decision of right-turning or left-turning, and the operation may be
ended when it can be regarded as the right-turning or left-turning
has been completed on the basis of the turning information produced
from the helm detecting unit 2b. In this case, the side is
monitored only at the time of right-turning or left-turning. During
the other case than the right-turning or left-turning, the CCD
cameras 11 may be oriented rear sideward to monitor the rear during
the driving or parking.
Further, in the embodiment described above, the ROM within the
.mu.COM 5 was adopted as a recording medium storing a processing
program of determining the danger of collision for the vehicle. For
example, a device capable of storing the processing program such as
a memory device, magnetic disk device, or an optical disk may be
adopted as the recording medium. The periphery monitoring apparatus
can be proposed in which the storage medium has only to be set to
start the processing program.
* * * * *